TROPOSPHERE REFRACTIVITY AND FICTITIOUS EARTH RADIO IN CUBA

Abstract

The variation in refraction index in the troposphere as a consequence of variation in temperature, humidity, and pressure with height, determines radio waves refraction. For taking into account this effect, traditionally, has been employed a fictitious radio term of the Earth a_e instead of the real radio during the calculation of electric field in the frequency bands of the radioelectric spectrum. In Cuba is a usual practice to use a_e of 8500 km (4/3 of the real radius of the Earth) during the determination of calculations of different radio services: in the case of coverage, in radio relay links, and in the range of radar stations. The objective of this article is to show, on the basis of existing data and measurements, the importance of using the necessary real value of a_e in our country. In this way, it is concluded that, due to the specific meteorological conditions of Cuba and of the Caribbean, an average value should be used, which in general is greater than 4/3, both in the routes over land and over the sea. As part of the proposed objective, other fictitious values of radii of a monthly and annual average of a_e are proposed, but differentiated, as far as possible, according to the region of the country or the sea. As a result of the proposal, the maximum line-of-sight distance, the intensity of the electric field received, and other radio technical parameters are increased, which is of interest in the projects which are being analyzed.